Question 1

Which of the following best describes the effect of constriction of the afferent arteriole on glomerular filtration rate (GFR)?

Accepted Answer

Constriction of the afferent arteriole decreases GFR by lowering glomerular hydrostatic pressure.

Question 2

A patient presents with a blood pH of 7.25, elevated $$\mathrm{CO_2$}$$, and normal bicarbonate levels. Which acid-base disorder is most likely present, and what is the primary compensatory mechanism?

Accepted Answer

Respiratory acidosis; compensation by renal reabsorption of $$\mathrm{$$HCO_3$$^-}.$$

Question 3

Which hormone increases water reabsorption in the collecting ducts by inserting aquaporins into the apical membrane of principal cells?

Accepted Answer

Antidiuretic hormone (ADH)

Question 4

Which of the following best explains why glucose is normally absent from urine?

Accepted Answer

Glucose is completely reabsorbed in the proximal convoluted tubule under normal conditions.

Question 5

A patient is given a loop diuretic that inhibits the Na$$^+-K$^+-2Cl$^-$$ symporter in the ascending limb of the nephron loop. What is the expected effect on urine concentration and why?

Accepted Answer

Urine becomes more dilute because the medullary osmotic gradient is reduced.

Question 6

Which of the following is a normal constituent of urine?

Accepted Answer

Urea

Question 7

Which structure is responsible for monitoring blood pressure and sodium concentration, and can release renin in response to low blood pressure?

Accepted Answer

Juxtaglomerular (granular) cells of the juxtaglomerular apparatus

Question 8

Which of the following best describes the difference between cortical and juxtamedullary nephrons?

Accepted Answer

Juxtamedullary nephrons have longer loops of Henle and are essential for producing concentrated urine.

Question 9

If a patient is experiencing dehydration, which hormone is most likely to be elevated to conserve water, and what is its effect on urine volume?

Accepted Answer

Antidiuretic hormone (ADH); decreases urine volume

Question 10

Which of the following equations correctly represents the calculation of net filtration pressure (NFP) in the glomerulus?

Accepted Answer

$$\mathrm{NFP} = \mathrm{HP}_g - (\mathrm{OP}_g + \mathrm{HP}_c)$$

Question 11

A patient with chronic vomiting is found to have a blood pH of 7.50, low plasma potassium, and elevated bicarbonate. Which acid-base disorder is present, and what is a likely cause?

Accepted Answer

Metabolic alkalosis; loss of gastric acid

Question 12

Which of the following best describes the role of aldosterone in the distal convoluted tubule and collecting duct?

Accepted Answer

Aldosterone increases sodium reabsorption and potassium secretion.

Question 13

Which of the following is the primary buffer system in the extracellular fluid?

Accepted Answer

Bicarbonate buffer system

Question 14

Which of the following best explains why protein is not normally found in urine?

Accepted Answer

Proteins are too large to pass through the filtration membrane under normal conditions.

Question 15

Which of the following best describes the effect of atrial natriuretic peptide (ANP) on the kidneys?

Accepted Answer

ANP decreases sodium reabsorption and increases urine output.

Question 16

Which of the following is the correct sequence of effectiveness for acid-base balancing mechanisms, from fastest to slowest?

Accepted Answer

Chemical buffers \u003e Respiratory compensation \u003e Renal compensation

Question 17

A patient with uncontrolled diabetes mellitus is found to have ketones in their urine. Which process is most likely responsible for this finding?

Accepted Answer

Increased filtration of ketones due to high plasma concentration

Question 18

Which of the following best describes the role of the vasa recta in the kidney?

Accepted Answer

The vasa recta maintains the medullary osmotic gradient by acting as a countercurrent exchanger.

Question 19

Which of the following is the primary cation in the intracellular fluid compartment?

Accepted Answer

Potassium ($$\mathrm{K^+})$$

Question 20

A patient with severe diarrhea is found to have a blood pH of 7.30, low bicarbonate, and normal $$\mathrm{CO_2$}. $$Which acid-base disorder is present, and what is the likely cause?

Accepted Answer

Metabolic acidosis; loss of bicarbonate from the gastrointestinal tract

Urinary System and Fluid, Electrolyte, and Acid-Base Balance: Study Guide

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